Inhibiting premature vulcanization of rubbers

ABSTRACT

Retarders of premature vulcanization of rubber, said retarders including N-alkylthio or N-arylthio sulfonamides and N-alkylthio or N-arylthio sulfamides, e.g., N-(n-butyl thio)-N-methylmethanesulfonamide.

Unified States Patent Shelton et a1.

[4 1 Sept. 9, 1975 INHIBITING PREMATURE VULCANIZATION OF RUBBERS RelatedU.S. Application Data Division of Ser. No. 26,431, April 7, 1970, Pat.No. 3,678,017.

Assignee:

U.S. Cl 260/453 R; 260/243 R; 260/247.1;

260/293.85; 260/301; 260/326.82 Int. Cl. C07C 119/18'; CO7C 119/20 Fieldof Search 260/453 R, 79.5 B

References Cited UNITED STATES PATENTS 9/1967 Klauke et a1 424/3213,344,153 9/1967 Kuhle et a1 260/453 R 3,396,007 8/1968 Strycker 424/3213,546,185 12/1970 Coran et a1.... 260/79.5

3,577,451 5/1971 Kuhle et a1. 424/321 3,703,500 1 1/1972 Nast et all260/453 R OTHER PUBLICATIONS Raban et a1., Stereochemistry at TrivalentNitrogen etc., (1968), JACS 90, pp. 2985-2986, (1968).

Ash et al., The lsomerization. of Sulphilimines, Part II, (1952), J.Chem. Soc., (1952), pp. 2792-2796.

Primary Examiner-Glennon H. Hollrah Attorney, Agent, or Firm-F. W.Brunner; J. A. Rozmajzl [57] ABSTRACT Retarders of prematurevulcanization of rubber, said retarders including N-alkylthio orN-arylthio sulfonamides and N -a1ky1thio or N-arylthio sulfamides, e.g.,N-(n-butyl thio)-N-methyl-methanesulfonamide.

5 Claims, N0 Drawings INHIBITING PREMATURE VULCANIZATION OF RUBBERS Thisis a division of application Ser. No. 26,43 l filed Apr. 7, 1970, andissued on July 18, 1972, as US. Pat. No. 3,678,107.

This invention relates to an improved vulcanizing process for rubber andto the rubber stocks obtained by using this improved process. Theinvention relates to improved accelerator-inhibitor combinations forrubbenThe invention also relates to new compounds useful as inhibitorsof premature vulcanization in rubber. More particularly the inventionrelates to a method for preventing the premature vulcanization of rubberstocks and to the rubber stocks obtained by using this method. I I vScorching during the processing of rubber is due to 'the premature orincipient vulcanization which may occur during any of the steps involvedin the processing prior to the'final vulcanization step, or duringstorage between said processing steps. Whereas a properly compoundedunscorched rubber formulation can be die-extruded or sheeted from acalender smoothly and without lumping, a scorched material often becomeswavy and lumpy after extrusion or sheeting, and must be discarded. M

An object of the present invention is to provide a method of inhibitingpremature vulcanization of rubber. Another object of the presentinvention is to provide scorch inhibitors and retarders for use inrubber processing. 7 I

According to the present invention there is provided a method ofinhibiting premature vulcanization of rubber containing a vulcanizingagent and an organic vulcanization accelerating agent which comprisesincorporating therein in an amount effective to inhibit prematurevulcanization, a compound selected from the group of retarders havingthe following structural formulae: I

and

wherein R and R are selected from the group consisting of substituted,e.g., with one or more halo, nitro, hy-' droxy or alkoxy groups, andunsubstituted, saturated and unsaturated hydrocarbon groups containingpreferably l. .to 20 carbon atoms. R is selected from the groupconsisting of R, R and wherein R and R are selected from the groupconsisting of hydrogen, R and R and R and R can bejoined through amember of the group consisting of CH O NH and S to constitute with theattached nitrogen atom a heterocyclic radical and wherein R is ahydrocarbon radical, substituted or unsubstituted, saturated orunsaturated containing 1 to 20 carbon atoms and wherein R "and R can bejoined through a CH group to constitute'with the S0 N group aheterocyclic radical. a

The Rsdescribed herein,i.e., R, R, R R, R and R mayall be differentin-ja particular compound. For example, although R is selected from thegroup consisting of R, R ,-etc., for a specific'compound, R may bemethyl, while R is ethyl and Rflis benzyl. Also, two R groups or two R.groups or two R groups within a compound need not be the same;

Preferredcompounds. include those whe'reR and R are radicalsselectedfrom the g-roupconsisting of alkyl l to 20 carbon atoms),cycloalkyl' (5 to 20wcarbon atoms) including alkyl substitutedcycloalkyls, aralkyl (7 to 20 carbon atoms), haloalkyl (l to 20 carbonatoms) such as chloroalkyl, aryl (6 to ,2O carbon atoms), alkylaryl (7to 20 carbon atoms), haloaryl (6 to 20 carbon ,atomsysuch as chloroaryl,nit-roaryl (.6 to 20 carbon atoms),.alkoxyaryl (7 to 20 carbon atoms)and alkenyl (3 to 20 carbon atoms) wherein R'is selected from the groupconsisting ofthe preferredR and R radicals described above and whereinwhen R is v R and R are selected from the group consisting of thepreferred R and R radicals described above or R and R are joined to forma ring selected from the group consisting of morpholino, piperidinoandpyrrolidino rings. i n

Preferably R is selected from the group consisting of alkylene radicals(l to 6 carbon atoms), cycloalk'ylene radicals (5 to 7 carbon atoms)andarylene radicals (6 to 20 carbon atoms) When R and R are joined toform, along with the S0 N group, a heterocyclic ring, preferably theremainder of the ring is ahydrocarbon containing 3 to 12 carbon atoms,e.g.,' to forrn a sultarn ring. For example, R and R may join to form atrimethylene or tetramethylene group.

One embodiment involves compounds where R is monohaloalkyl ('l'to"carbon atoms), preferably a monochloro'alkyl. Examples of such radicalsinclude 1-( 2-chlorobutyl)- and 2-( l-chlorobut'yl)-f Most preferredarethe retarders wherein R is selected from the group consisting of methyl,ethyl, isopropyl, n-butyl, t-butyl and other alkyls having from 1 to 6carbon atoms, phenyl, p-tblyl, p-chlorophenyl, dimethylamino,morpholino, piperidono and trichloromethyl radicals; wherein R isselected from the group consisting of methylj'ethyl,isopropyl, n-butyl,t-butyl and other alkyls having from'j l to 6 carbon atoms, cyclohexyl,phenyLp-tolyl,p-chlorophenyl and allyl radicals and'wherein R isselected from the group consisting of methyl, ethyl, isopropyl, n-butyl,t-butyl and other alkyls having from 1 to 6 carbon atoms includingmonochloroalkyls, benzyl, cyclohexyl, 2-

This invention is applicable to rubber mixes containingsulfur-vulcanizing agents, peroxide-vulcanizing agents, organicaccelerators for vulcanization and antidegradants, neither being theinhibitor used. For the purposes of this invention, sulfur-vulcanizingagent means elemental sulfur or sulfur containing vulcanizing agent, forexample, an amine disulfide or a polymeric polysulfide. The invention isapplicable to vulcanization accelerators of various classes. Forexample, rubber mixes containing the aromatic thiazole acceleratorswhich include benzothiazyl-2'monocyclohexyl sulfenamide,Z-mercaptobenzothiazole, Ntert-butyl-2 benzothiazole sulfenamide,2-benzothiazolyl diethyldithiocarbamate and 2-(morpholinothio)benzothiazole can be used. Other thiazole acceleratorswhich may be used include 2-(aminodithio)-thiazoles andZ-(aminotrithio)-thiazoles such as 2-(morpholinodithio benzothiazole.Amine salts of mercaptobenzothiazole accelerators for example, thet-butyl amine salt of mercaptobenzothiazole, and like salts ofmorpholine and 2,6-dimethyl morpholine can be used in the invention.Thiazole accelerators other than aromatic can be used. Stocks containingaccelerators, for example tetramethylthiuram disulfide,tetramethylthiuram monosulfide, aldehyde amine condensation products,thiocarbamylsulfenamides, thioureas, xanthates, and guanidinederivatives are substantially improved during the process of ourinvention.

.The inhibitors of the invention can be used in natural and syntheticrubbers and mixtures thereof. Synthetic rubbers that'can be improved bythe process of this invention include cis-l,4-polybutadiene, butylrubber, ethylene'propylene terpolymers, polymers of 1,3- butadienes, forexample, 1,3-butadiene itself and of isoprene, copolymers of1,3-butadiene with other monomers, for example, styrene, acrylonitrile,isobutylene and methyl niethacrylateEthylene propylene terpolymers, forexample ethylene/propylene/dicyclopentadiene terpolymers can benefitfrom the present invention. The invention is of particular value withreference to the diene rubbers and the term rubber is used herein toinclude both diene rubber and other rubbers.

The following Examples 1 to 6 illustrate the prepara tion of variousretarders which may be used within the practice of the presentinvention. These examples illustrate, but do not limit, the practice ofthe present invention.

EXAMPLE 1 To prepare N-cyclohexyl-N-(phenylthio)- methanesulfonamide,0.22 mole of chlorine gas is passed into 250 ml. of a carbontetrachloride solution containing 22 grams (0.20 mole) of thiophenol.The addition time for chlorine is about one-half hour. The reactiontemperatureis held at 20 C. during the addition. The resulting orangebenzenesulfenyl chloride solutionis then warmed to 0C. and purged withnitrogen to remove hydrogen chloride gas. The sulfenyl chloride solutionis added over a 50 minute period to a stirred mixture of 36.3 grams(0.205 mole) of N-cyclohexylmethanesulfonamide and 30.3 grams (.30 mole)of triethylamine in'l80 ml. of benzene at 10 to C. After the addition,the reaction mixture is stirred an additional 50 minutes at roomtemperature and poured over one liter of water. The organic phase issubsequently washed three times with 200 ml. portions of water, driedover anhydrous sodium sulfate, filtered and stripped of solvents atreduced pressure. The residue is a viscous brown oil which deposits awhite crystalline solid when mixed with n-octane. Filtration of theoctane slurry gives 34.5 grams (60%) of product with a melting point of82 to 835C. Analysis of this product shows 22.9 percent sulfur and 5.01percent nitrogen. Calculated percentages for C H NO S are 22.5 percentsulfur and 4.91 percent nitrogen. The infrared and proton resonancespectra are consistent with the proposed structure.

EXAMPLE 2 To prepare N-(n-butylthio)-N-methylmethanesulfonamide, 0.35mole of chlorine gas is added over aone-half hour period to a solutionof 0.35 mole (62.5 grams), of n-butyldisulfide in ,550 ml. carbontetrachlorideat 20 to.l0 C. The resulting nbutanesulfenyl chloridesolutionis then added over a 0.5 hour period to a suspension of 0.70mole of the sodium salt of N-methyl-methanesulfonamide in 400 ml. oftoluene, keeping the temperature at 30 C. The reaction mixture isstirred for one hour after addition. of the sulfenyl chloride and thenwashed three times with one liter portions of water. The organic layeris separated and dried over anhydrous sodium sulfate, filtered, and thetoluene and carbon tetrachloride evaporated under reduced pressure atless than 60 C. The residue is a yellow to orange liquid, 136.5 grams(99%) which solidifies at 1 0 to 5 C. Recrystallization from diethylether gives a faintly yellow liquid with a melting point from 3 to 1 C.and a refractive index (r1 of 1.4846. Gas chromatographic analysis showsgreater than 97 percent purity. The infrared and proton resonancespectra are consistent with the proposed structure. Calculatedpercentages for C H NO S are 7.10 percent nitrogen, 32.51 percentsulfur, 36.53 percent carbon, 7.66 percent hydrogen. and 16.22 percentoxy gen. An elemental analysis of the recrystallized product showed 7.12percent nitrogen, 32.54 percent sulfur, 36.34 percent carbon and'7.67percent hydrogen and thereby indirectly, 16.33 percent oxygen.

EXAMPLE 3 To prepare N-(cyclohexylthio)-N,N',N-trimethylsulfamide 0.35mole of chlorine gas is added over a one-half hour. period to a solutionof 0.35 mole grams) dicyclohexyldisulfide in 450 ml. of carbontetrachloride at 20 to l0 C. The resulting cyclohexanesulfenyl chloridesolution is added over a 20 minute period to a suspension of 0.70 moleof the sodium salt of N,N,N'-trimethylsulfamide in 200 ml. of toluene at25 to 30 C. The reaction mixture is then stirred an additional 0.75 hourat 35 to 40 C. The product is washed 3 times with 1 liter portions ofwater, and the organic phase separated, dried over anhydrous sodiumsulfate, and filtered. The solvents are removed under reduced pressure,leaving 174 grams (99 percent) of a pale yellow liquid, with a meltingpoint of about 0 C. This product is recrystallized in petroleum ether togive a faintly yellow liquid, having a. melting point of 10 to 13 C.Analysis of the recrystallized product shows 10.89 percent nitrogen. Thecalculated percentage for C H N O S is l 1.10 percent nitrogen. Gaschromatographic analysis shows greater than 99 percent purity. Theinfrared and proton resonance spectra are consistent with the proposedstructure.

EXAMPLE 4 To prepare N-(n-butylthio)-N-methyl-ptoluenesulfonamide, asolution of 0.25 mole of nbutanesulfenyl chloride in 300 ml. of carbontetrachloride is prepared in a manner analogous to Example 1. Thissolution is then added to a suspension of 0.27 mole of the sodium saltof N-methyl-p-toluenesulfonamide in 170 ml. of toluene overa one-halfhour period at 28 to 31C. After addition of the sulfenyl chloride, themixture is stirred for 1 hour at 28C. The reaction mixture is washedwith one liter of a 3 percent sodium hydroxide solution," then threetimeswith one liter portions" of 'water. The organic phase is separated,dried over anhydrous sodium sulfate, filtered, and stripped of solventsunder reduced pressure. A light yellow liquid residue, 63 grams (91percent) is obtained. This mate rial solidifies on cooling, and has amelting point of about 25 to 30C. Recrystallization from petroleum ethergives awhite crystalline product, having a melting point of 33 to 34C.Analysis of the recrystallized sample shows 5.03 percent nitrogen. Thecalculated percenta ge' for C, H NO S is 5.07 percent nitrogen.

EXAMPLE 5 To prepare N-(p-tolylthio)-N-methylmethanesulfonamide, 40.4grams (0.30 mole) of freshly distilled sulfuryl chloride is added to asolution of 73.9 grams (0.30 mole) of p-tolyl disulfide in 200 ml.dichloromethane, keeping the temperature below 20 C. After the addition,the solution is stirred for 1 hour. The solvent is then removed underreduced pressure. p-Toluenesulfenyl chloride, a red liquid, is obtainedin substantially quantitative yield. This sulfenyl chloride is added toa toluene suspension of 0.32 mole of the sodium salt ofN-methyl-methanesulfonamide over a onehalf hour period at 30 C. Themixture is then stirred an additional 2 hours at room temperature, andwashed 3 times with 500 ml. portions of water. The organic layer isseparated, dried over anhydrous sodium sulfate, filtered, and thetoluene evaporated under reduced pressure. The residue weighs'61 grams(88%) and is a light yellow solid. The solid is recrystallized fromdiethyl ether to give a white crystalline product having a melting pointof 73 to 74 C. Analysis shows 5.72 percent nitrogen. The calculatednitrogen for C H NO S is 6.06 percent.

EXAMPLE 6 To prepare N-( benzylthio )-N-methylbenzenesulfonamide, 0.13mole of chlorine gas is added over a one-half hour period to a solutionof 3l grams (0. l 3 mole) benzyl disulfide in 300 ml. of carbontetrachloride at C. The resulting phenylme-' thanesulfenyl chloridesolution is then added over a one-half hour period to a suspension of0.28 mole of the sodium salt of N-methyl-benzenesulfonamide at atemperature of from 0to C. After addition of the sulfenyl chloride, thereaction mixture is stirred 2 hours at 25 to 30 C. The mixture is thenwashed with 1 liter of 3 percent sodium hydroxide, followed by washing 3times with one liter portions of water. The organic layer is separated,dried over anhydrous sodium sulfate, filtered, and the solvents removedunder reduced pressure. The residue is 65.2 grams (88%) of orange liquidwhich solidifies on standing. Recrystallization from carbontetrachloride gives a white crystalline solid with a melting point of 71to 72 C. Analysis shows 22.0 percent sulfur and 4.73 percent nitrogen.Calculated percentages for C H NO S are 21.8 percent sulfur and 4.78percent nitrogen.

The other compounds included within the practice of the presentinvention can be prepared by using the same or similar techniques asdescribed in the preceding working examples. Synthetic routes to thesecompounds are not limited however to these particular reactions andprocedures.

Tables I to IX illustrate the use of the retarders with a variety ofrubber stocks and accelerator systems. The compositions are intendedonly to be illustrative of the practice of the present invention and notlimiting. The numbers immediately preceding or following the componentsof the compositions are parts by weight. Unless otherwise indicated, allparts are parts by weight. Mooney Scorch tests were performed using thelarge rotor as described in ASTM D 1646-61. A recorder was employed tocontinuously plot viscosity versus time. The number of minutes (trequired for the viscosity curve to rise 5 points above the minimum wastaken as a measure of scorch inhibition. Larger values for L, indicate agreater resistance to scorch or premature vulcanization.

Supplementary data on scorch delay and vulcanizing characteristics wereobtained with a Monsanto Oscillating Disc Rheometer, as described byDecker, Wise, and Guerry in Rubber World, page 68, December 1962.Pertinent data from this instrument are: 1 the minutes required for theRheometer torque curve to rise 4 units above the minimum torque value,and the minutes required for the torque curve to reach 90 percent of thedifference between the maximum and minimum torque values.

The time, serves as a measure of scorch delay similar to t from theMooney scorch measurement. The r value is considered to be the timerequired to reach the optimum vulcanized state. The difference,(r,,.,t,) is indicative of the time necessary for actual vulcanizationto take place after the scorch delay period has ended, i.e., is arelative measure of vulcanization rate. Scorch inhibitors which increaset but do not greatly increase (t rn) are preferred since these impartprocessing safety, yet do not require greatly extended vulcanizationtimes.

The tensile strength, elongation, and 300 percent modulus were obtainedaccording to standard test procedures wherein dumbbell samples were diedfrom vulcanized sheets and tested in a conventional tensile tester. Thisprocedure is more fully described in New Autographic Machine for TestingTensile Properties of Rubber, by G. .l. Albertoni, Industrial andEngineering Chemistry, Analytical Edition, Vol. 3, p. 236, 193 1. Teststocks were vulcanized either for arbitrary times of 15, 30, 60 andminutes, or for the times and 20 as determined from the Rheometercurves.

. Table l illustrates the use ofN-(n-butylthio)-N-methyl-methanesulfonamide and N-( cyclohexylthioN,N,N' -trimethylsulfamide as scorch inhibitors in natural rubber stocksaccelerated by 2-(morpholinothio)- benzothiazole.

ABLE 1 Components and Parts. Common to All Stocks 100 Natural Rubber 50High Abrasion Furnace Black 3.0 Hydrocarbon Softener 3.0 Stcaric Acid3.0 Zinc Oxide 1.0 Amine Typc Age Resistor 2.5 Sulfur 0.52-(Morpholinothio) hcnzothiazolc Stocks Returders A B D E F GN-(n-butylthioJ-N-mcthylmcthuncsulfonumidc 0.25 0.50 1.00N-(cyclohexylthio)N.N,N'-

trimcthylsulfamidc 0.25 0.50 1.00 Mooney Scorch at 121 C. e

I t 27.2 46 46 60 31.3 36.9 52.4 Monsanto Rheomctcr at 1 t, 15.4 28.334.6 50.2 17.5 19.5 29.2 t 43.3 60.3 67.2 85.6 I 50.0 v 54.9 70.9 (r -t27.9 32.0 32.6 35,4 32.5 E 35.4 41.7 Physical Properties Vulcanized at135C for Time (min.) Shown: i h

Tensile Strcngth.psi I v 2600 600 530 500 1-600 900 710 3500 3460 2200740 .3740 I 3430 1950 60 .3600 3.560 3740 3700 3790 3550 4050 120 35903600 3400 3400 3360 3360 3460 t Elongationf/l I 15 590 570 580 630 575520 580 30 520 585 560 H 640 565 555 515 60 460 475 500 540 2480 480 510y 120 4 5 450 440 430 435 445 460 3007r Modulus,psi V g Y e L 15 1020 v170 170 140 e 560 325 220 Both test compounds showed a high degree ofeffec- Components Pans tiveness as scorch inhibitors.N-(n-butylthio)-N-methyl-methanesulfonamide was particularly effectivesince 35. 3 100 1 High Abrasion Furnace Black 3 50 It gave a largescorch delay with only a small increase Hydrocarbon Softener 3 in actualvulcanization time (r -t From the data, it stwic Acld 3 Zinc Oxide 3 1Sevident that these inhibitors have virtually no detri- Amine Type AgeRegister. 1 mental effect on the ultimate physical properties of theSulfur 1 i i y vulcanized Stocks. 2-(morphollnodithio)-benzoth1azole 10.5 e

TABLE II Rctardcrs: 'C

N-(n-huty1thio)-N,N1.N'-trimcthyl sulfamide 1.0N-(n-buty-1thio)-N-mcthy1mcthancsulfonumidc 1.0 Muoncy Scorch at 121 C.t 24.2 57.4 60 Monsanto Rhcomctcr at 135'? C t 14.0 24.0 31.0 1,, 50.570.4 13.0 4. 36.5 46.4 42.0 Physical Properties Vulcanized at 135C. forTime (min.) Shown:

Tensile Strength. psi 15 2350 575 500 .30, 3700 2025 1875 60 3650 36503510 120 3500 3700 3375 Elongutionf/l 15 620 600 580 30 560 560 555 60460 510 485 120 450 465 421) 300% Modulus. psi 15 700 180 I 30 1580 700650 2100 2025 2050 2225 2360 2275 The stocks described in Tables n, Inand 1V 'al1'contained the following components:

From Table 11 it is seen that N4nbm lthidynhdfin trimethyl sulfamide andN1-(n-butylthio)-N-methyll l 2 methanesulfonamide are effectiveinhibitors when used The stocks used for Tables V and VI had thefollowwith the accelerator 2-(morpholinodithi0)- ing components incommon. benzothiazole.

TABLE III Stocks Retarders: A B C D E N-( hcnzylthio)-N-methylbenzencsulfonamide I 0.5 l .0 N-( nbutylthio )-N-( n-butylmethanesulfonamide v 0.5 N-(henzyllhiol-N-isopropyl- 3p-lolucnesulfonamide Mooney Scorch at l2 C. t 24.6 36.6 47.8 39.8 2.4Monsanto Rhcomeler at 135 C. t, l4.3 21.9 28.0 214 I834 t 46.9 58.2 67.857.5 54.] 32.6 36.3 39.8 36.1 35.3

Physical Properties Vulcanized at |35C. for Time (min.) Shown:

Tensile Strength. psi I5 2640 750 580 760 820 30 3600 3590 3060 34603725 -l760 I640 H70 1440 I610 60 2l80 2350 2200 2160 2220 v f I20 2l3022l0 2200 2125 2200 T-ABLEW.

' Stocks Retarders: A B C D N-(n-hutylthio)-N-methylv il-fl.

p-toluencsulfonumidm 0.5 N-( p-tolylthio)-N-methylv methunesulfonamide0.5 N-( n-hutylthio )-N-mcthyl- 4-morpholine sulfonamidc Mooney Scorchat l2l C. I 27.2 44.8 43.1 41.2 Monsanto Rheometer at l C. t 15,5 23.823.5 26,0 t 52.5 62.0 59.5 66.5 "(t,,-.,-t,,) 37.0 38.2 36.0 40.5Physical'Properties Vulcanized at l35C. for Time (min.) Shown:

Tensile Strength. psi I5 3270 l060 490 750 30 3690 3590 3290 35 l() 603600 3400 3580 3560 l'20 '3330 3390 3450 3350 Elongation, 7r 1 I5 630'600 565 595 30 570 1 585 575 610 60 505 475 495 495 120 455 470 4x0 460300% Modulus. psi l5 I250 270 I 210 30 I825 l6l0 I580 I500 2 I00 2] I02150 2050 I20 I975 2075 2100 2] 10 Components Parts Tables Ill and IVprovide additional examples of the Oil Extended Styrene-Butadicne Rubberl7 l2 137.5 use of inhibitors of this invention with natural rubberSupcr Abram" Fumucc muck Linc Oxide 5 stocks accelerated by 2-(morpholinod|th|o)- swam Add 2 benzothiazo|e Amine Type Age Resister l.5

TABLE V Stocks Retarder: A B C D E F G H N-(n-butylthio)-metllanesulfonamide 1.0 0.5 0.5 0.5 Accelerator:

2-( morpholinodithio henzothiazolc 1.2 1.2 2-( morpholinothiohenzothiazole 1.2 1.2 N-cyclohexyl-Z-benzothiayolesull'enamide 1.2 1.2 22'-dithio bis- (henzothiuzole) 1.0 1.0 Diphenyl guanidine 0.75 0.75Mooney Scorch at g 132 C. t 19.2 34.4 35.9 54.1 26.0 40.5 11.1 18.5Monsanto Rheometer y at 143 C. t, 16.5 i 27.0 30.0 41.5 12.5 3310 10.918.5

{510 41.2 51.9 51.5 64.1 44.6 56.5 25.0 33.0 (t -t 24.7 24.9 21.5 23.623.1 23.5 14.1 14.5 Physical Properties Vulcanized at 143 C. for Time(min.) Shown:

Tensile Strengthpsi y 4 I5) 3000 2940 2910 2860 2940 -2930 2750 27602(tim) 3010 3050 2820 2930 2950 v 3000 2675 2600 Elongation/71 K 5X0 550530 570 585 575 520 520 2(t 525 -515 470 515 520 525 440 435 300%Modulusmsi v t,, 1350 1370 1440 1290 1280 1340 1390 1375 2( Km) 15801575 .1650 1525 1550 1530 1660 1610 TABLE VI Stocks Rctarders: A B C D EF G H N-(ptolylthio) N-methyl methanesulfonamide N-( n-butylthiotoluenesulfonamide 0.25 0.5 0 5 l,() Accelerators:

2-( morpholinodithio benzothiazolc 1.2 1.2N-(yclohexyl-2-henzothiazolesulfenamitle 1.2 1.2 1.2 2 2-dithiobis-(henlothinzole) 1.0 1.0 1.0 Diphenyl guanidine 0.75 0 75 0.75 MooneyScorch at 132 (4 t; 19.2 29.3 26.0 31.1 37.3 11.1 16.3 26.4 MonsantoRhcometer at 143 C. t, 16.5 23.6 21.5 26.2 30.2 10.9 16.2 22.0 tw- 41.246.2 44.6 49.2 53.1 25.0 31.5 38.3 (g -t 24.7 22.6 23.1 23.0 22.9 14.115.3 16.3 Physical Properties Vulcanized at 143 C. for Time (min.)Shown:

Tensile Strenglhpsi 1m 3000 3080 2940 2820 2950 2750 2530 2700 2(1 11)3010 2850 2950 2940 2860 2675 2410 2700 Elongation. '71

fim 580 600 585 540 575 520 470 525 2mm) 525 505 520 515 495 440 425 480300% Modulus psi Table V illustrates the use of N-(n-butylthio)-N-methyl methanesulfonamide in the styrene-butadiene rubber stock withfour different accelerator systems. The data show the compound to be anexcellent scorch inhibitor in all the test stocks. Significantly,neither the vulcanization times (r -t nor the ultimate physicalproperties are altered to any great extent by the inhibitor.

In Table VI, the use of two additional scorch inhibitors in thestyrenebutadiene rubber stock is illustrated. Again significantincreases in scorch delay were obtained and accompanied by only smallchanges in TABLE V11 1 Components and Parts, Common to All Stockscis-l,4-polyisoprene, 50 High Abrasion Furnace Black, 3 HydrocarbonSoftener, 3 Stearic Acid, 3 Zinc Oxide, 1 Amine Type Age Resister. 2.5Sulfur Stocks Rclarder: A B C D E F G N-( n-hutylthio )-N-methylmethanesulfonamide 0.5 1.0 0.25 0.5 1.0 Accelerator:

2( morpholinodithio benzothiazole 0.5 0.5 0.5N-cyelohexyl-Z-benzothiazolesulfenamidc 0.5 0.5 0.5 0.5 Mooney Scorch at121C.

t 22.1 39.6 60 22.8 40.5 60 60 Monsanto Rhcometcr at 135 C. L 13.0 22.532.2 14.0 24.9 35.0 49.4 tm 34.8 49.8 64.1 33.5 46.8 59.1 76.0 (t -t21.8 27.3 31.9 19.5 21.9 24.1 26.6 Physical Properties Vulcanized at 135C. for Time (min.) Shown:

Tensile Strength.psi

t 3600 3680 3730 3490 3775 3480 3530 3715 3530 3400 3550 3380 3580 3500Elongation. 7( t 600 570 565 580 590 590 530 20 0) 570 510 480 530 525525 510 300% Modulus.psi w 1450 1750 1650 1450 1625 1690 1680 20 17001900 1900 1680 1620 1760 1840 A substantial degree of inhibition isnoted with two The retarder is effective with both accelerator sys-TABLE V111 Components and Parts, Common to All Stocks 90cis-l,4-polybutadiene, 10 Natural Rubber, Intermediate Super AbrasionFurnace Black, 10 Naphthenic Processing Oil, 3 Zinc Oxide, 3 StearicAcid, 1

terns illustrated. vulcanization times (1 -1 show little change in thepresence of the retarder. The physical properties of the vulcanizedstocks containing retarder appear to show a slight improvement over thecontrols.

Table IX serves to demonstrate that the scorch inhibitors of thisinvention may also be used in rubbers of the ethylene-propyleneterpolymer (EPDM) type.

TABLE 1X Components and Parts, Common to All Stocks EPDM (Nordel 1070),80 Intermediate Super Abrasion Furnace Black, 50 Napthenic SofteningOil, 5 Zinc Oxide, 1.5 Tetramethyl thiuram Monosulfide,

Amine Type Age Resister, 2.5 Sulfur 0.5 Z-Mercaptobenzothiazole, 1.3Sulfur Stocks Retarder: A B C D E F N-( ben zylthio )-N-methylbenzenesulfonamide 0.5 l .0 0.25 0.5 Accelerator:

2-( morpholinodithio benzothiazole 0.5 0.5 0.5Ncyclohexyl-2-benzothiazolesulfcnamide 0.5 0.5 0.5 Mooney Scorch at132C. t,, 17.7 22.4 26.7 14.1 20.7 25.9 Monsanto Rheomctcr at C. t. 9.210.6 11.6 8.0 9.8 l 1.8 am 24.1 26.2 27.5 22.7 23.8 24.8 (u -t 14.9 15.615.9 14.7 14.0 13.0 Physical Properties Vulcanized at 150C. for Time(min.) Shown:

Tensile Strengthpsi tm 2200 2550 2275 2375 201m) 2090 2600 2160 2500Elongation, '7: I. 605 660 765 725 20) 485 575 555 595 30071 Moduluspsit 660 700 525 550 mm.) 900 920 7x0 x10 Stocks Returder: A B C D E N-(n-butylthio )-N-melhylmethanesulfonamidc 0.5 1.0N-(eyclohexylthio)-N.N.N'

lrimethylsulfamide 0.5 1.0 Mooney Scorch at 135 C. t; 16.0 19.7 30.520.9 25.8 Monsanto Rheometer at C. t 7.1 8.3 l 1.4 9.0 10.5 1m 14.3 16.020.3 17.1 18.8 (tmrh) 7.2 7.7 8.9 8.1 8.3 Physical Properties Vulcanizedat 160 C. for Time (min.) Shown:

Tensile Strength, psi 1m 2350 2440 2325 2300 2300 2(190) 2470 2400 23902360 2310 Elongation. '/r I, 730 780 805 735 740 2K 575 660 700 630 645300% Modulus. psi t 450 450 450 500 460 2(( 860 670 650 700 730 Theabove examples are not intended to be limiting, but rather illustrative.Any of the. retarders, accelera tors and rubbers described earlierherein can be substiv tuted in the preceding examples to obtainretardation effects. In addition the levels of the retarders and othercomponents in said examples could be altered in accordance with thegeneral teachings herein and retardation effects would be obtained.Peroxides, such as dicumyl peroxides, could also be used in saidexamples with or without the presence of sulfur and/or sulfur donatingcompounds.

Retarders within the practice of the present invention other than thosedescribed in the preceding examples have been synthesized and testedpositively as retarders.

An SBR-l7l2 (oil-extended butadiene-styrene rubber) stock has also beentested with no sulfur present using 2-(morpholinodithio)-benzothiazoleas both sulfur donor and accelerator using N-(n-butylthio)-N-' methylmethanesulfonamide as the retarder. Although the stress-strainproperties of the vulcanizate were adversely affected, positiveretarding effects were obtained.

The retarders of this invention may be used at concentrations of from010 part to 5.0 parts by weight of retarder per 100 parts by weight ofrubber and even from 0.05 to 10.0 parts. Preferably the concentrationranges from 0.25 to 5.0 parts, more preferably from 0.25 to 3.0 partsand most preferably from 0.25 to 1.50 parts.

The retarders of the present invention are preferably added to therubbery polymer at the same time that the accelerator is added, althoughthis order of addition is not necessary to the successful utilization ofthe compounds of thisinvention.

The data in the preceding working examples are representative of thefact that the compounds of the present invention are effective asretarders in the presence of organic accelerators whether they arediaryl guanidines such as diphenylguanidine, or thiazoles, morespecifically benzothiazyl amino disulfides, such as 2-(morpholinodithio)-benzothiazole, or thiazoles (also sulfenamides), morespecifically thiazolesulfenamides, and even more specificallybenzothiazolesulfenamides such as 2-( morpholinothio)-benzothiazole andN- cyclohexyl-2-benzothiazolesulfenamide, i.e., regardless of what typeof organic accelerator is used. Thiuram sulfides such as tetramethylthiuram monosulfide and disulfide and tetraethylthiuram monosulfide anddisulfide may also be used as well as other benzothiazolesulfenamidessuch as N-(t-butyl)-2-benzothiazolesulfenamide.

Various organic accelerators useful within the practice of thisinvention are described and illustrated in the Vanderbilt RubberHandbook, 1968 Edition, R. T. Vanderbilt Company, Inc., particularly atpages 242 to 244 and also in the bulletin of the Elastomer ChemicalsDept. of the E. I. du Pont de Nemours and Co. (Inc.) entitled,Accelerators, Vulcanizing Agents and Retarders, Brochure N0. SD A54457."

The polymers in which the retarders of the present invention areincorporated remain suitable for their art recognized uses, e.g., intires and industrial products.

While certain representative embodiments and details have been shown forthe purpose of illustrating the invention, it will be apparent to thoseskilled in this art that various changes and modifications may be madetherein withoutideipartingfrom the-spirit or scope of the invention.

What is claimed iszjg. l. A compound selected from the group consistingof 5 compounds having the following structural formulae:

wherein R is selected from the group consisting of alkyl radicals havingfrom 1 to 20 carbon atoms, cycloalkyl radicals having from 5 to 20carbon atoms, phenylalkyl radicals having from 7 to 20 carbon atoms,chloroalkyl radicals having from 1 to 20 carbon atoms, phenyl,alkylphenyl radicals having from 7 to 20 carbon atoms, chlorophenylradicals, nitrophenyl radicals, alkoxyphenyl radicals having from 7 to20 carbon atoms. and

wherein R is selected from the group consisting of alkyl radicals havingfrom 1 to 20 carbon atoms, cycloalkyl radicals having from 5 to 20carbon atoms, phenyl, alkylphenyl radicals having from 7 to 20 carbonatoms, chlorophenyl radicals, nitrophenyl radicals and alkoxyphenylradicals having from 7 to 20 carbon atoms, wherein R R and R areselected from the group consisting of alkyl radicals having from 1 to 20carbon atoms, cycloalkyl radicals having from 5 to 20 carbon atoms,phenylalkyl radlicals having from 7 to 20 carbon atoms, chloroalkylradicals having from 1 to 20 carbon atoms, phenyl, alkylphenyl radicalshaving from 7 to 20 carbon atoms, chlorophenyl radicals, nitrophenylradicals and alkoxyphenyl radicals having from 7 to 20 carbon atoms andwherein R is selected from the group consisting of alkylene radicalshaving 1 to 6 carbon atoms and cycloalkylene radicals having 5 to 7carbon atoms.

2. The compound according to claim 1 wherein the compound has thefollowing structural formulaN-(cyclohexylthio)-N-methyl-p-toluenesulfonamide 5. The compoundaccording to claim 1 wherein the and compound isN,N-di(n-butylthio)-N,N'-ethylenebis(p-N,N'-di(benzylthio)-N,N'-ethylenebis(ptoluenesulfonamide).

toluenesulfonamide).

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECT-ION PATENT NO.3,90%,66H DATED September 9, 1975 INVENTOR(S) 7 James R. Shelton andRoger J. Hopper It is certified that error appears in theabove-identified patent and that said Letters Patent are herebycorrected as shown below:

Table V, Stock E, "12.5" should read 21. 5

Table VI; Stock B, opposite first retarder is blank but should read 1.0Stock C, opposite first retarder reads "1.0" but should be blank.

Claim 2, column 18, line 53, "claim 29' should read claim 1 Signed andSalad this twenty-third D ay Of December 1 975 [SEAL] A ties t:

RUTH C. MASON C. MARSHALL DANN Arresting Officer Commissioner ufPatentsand Trademarks

1. A COMPOUND SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS HAVING THEFOLLOWING STRUCTURAL FORMULAE:
 2. The compound according to claim 1wherein the compound has the following structural formula
 3. Thecompound according to claim 1 wherein R is selected from the groupconsisting of phenyl and p-tolyl radicals, R1 is selected from the groupconsisting of methyl, ethyl, isopropyl and phenyl radicals and R2 is analkyl radical having from 1 to 6 carbon atoms.
 4. The compound accordingto claim 1 wherein the compound is selected from the group consisting ofN,N''-di(n-butylthio)-N,N''-ethylenebis(p-toluenesulfonamide),N-(cyclohexylthio)-N-methyl-methanesulfonamide,N-(n-butylthio)-N-methyl-methanesulfonamide,N-(benzylthio)-N-methyl-methanesulfonamide,N-(benzylthio)-N-methyl-benzenesulfonamide,N-(n-butylthio)-N-methyl-p-toluenesulfonamide,N-(cyclohexylthio)-N-methyl-p-toluenesulfonamide andN,N''-di(benzylthio)-N,N''-ethylenebis(p-toluenesulfonamide).
 5. Thecompound according to claim 1 wherein the compound is N,N''-di(n-butylthio)-N,N''-ethylenebis(p-toluenesulfonamide).